We're told Masika explains in the papers, she and Fetty met last year and from June 28 until July 15 had "sexual relations on numerous occasions." She also states he was her only partner during that period. Ditto for the 4 months prior.

Bottom line for Masika -- who's 7-8 months along -- Fetty's her only candidate for the daddy.

Masika also wants Fetty to pay pregnancy expenses and child support once the baby arrives. She lists some monthly expenses ... including $4,500 for rent, $820 for a housekeeper and $2,000 for clothes.We're told she says she's dropping $17k per month on expenses.

Masika wants the court to grant her full legal and physical custody as soon as she pops out baby Fetty.

Late last year, the former Love & Hip Hop star claimed to be six months pregnant for Fetty Wap. The two worked on the new song Ándale together, and things allegedly went from the studio to the bedroom that same day, which is when Masika says she got pregnant. Fetty asked Masika why she didn't terminate the pregnancy when she found out, to which she responded that she believes abortion is murder.